1. Field of the Invention
The present invention relates to an apparatus and method for recording and/or reproducing a digital signal, and more particularly to such an apparatus and method suitable for use in recording and/or reproducing a digital signal transferred from a computer or the like.
2. Description of the Prior Art
In practice, data stored in a hard disk or the like of a computer can be transferred to and recorded by a data streamer (data-recorder) once a day so as to protect the data or back up the same.
For this operation, or as a data recorder, analog audio tape recorders have been conventionally used in many cases. However, analog tape recorders have disadvantages in that they need an excessive amount of a recording medium or magnetic tape for recording and operate at a quite low data transferring rate upon recording, so that it takes too much time to transfer and record such data information. Moreover, analog tape recorders have problems, e.g. the starting point of a desired portion of the recorded data information cannot be rapidly searched for, and so on.
Thus, to overcome the above-mentioned problems, it is thought to utilize a helical-scan type DAT (digital audio tape recorder) using a rotary head, that is, a so-called recently commercialized DAT as a data recorder. Such data recorders utilizing a DAT are described in U.S. Pat. Nos. 4,873,589, 4,899,232, 4,876,616, and 5,012,459 by one of the assignees of the present application.
To utilize the DAT as a data recorder, data transferred from a host computer is transformed in accordance with a DAT format before recording. In the DAT format, one frame is made up of two oblique tracks formed by one rotation of two heads respectively having a different azimuth angle with respect to the recording tape. 16-bit PCM audio data, which has been interleaved, and auxiliary sub-data are recorded in this one frame area as a unit. During recording, there are formed in each track a main area for recording the PCM data and a sub-area for recording the sub-data.
When the DAT is used as a data recorder, data sent from a computer is continuously recorded on a magnetic tape several times, i.e., so-called multiple writing is performed in order to eliminate the influence of errors such as drop-out and to protect the data. When the data is multiply written, signal processing must be facilitated.